Ok, this is a big, big topic, I just want to offer a very simple angle, definitely not the whole story or the only reason, but a logical one for me.
If Jesus was a man as stated in Philippians 2:7-8 (something that I doubt anyone will disagree with) and he was “tempted in every way, just as we are” (Hebrews 2:18) “yet he did not sin”, then can we all agree that he was not deserving of death [if “the wages of sin is death” (Romans 6:23)].
If Jesus were to be left in this state – being tempted as a man, just like we are, yet never giving in to that temptation, he would be undeserving of death, therefore remain alive, but still be tempted because he was human.
Doesn’t that seem like a more cruel and callous thing for God to do than to allow other humans to kill him?
Once he was raised into his new body, temptation was no longer a problem as he was changed (the clearest evidence of that change was the ability to pass through locked doors – John 20:26) but before the death and resurrection, he was still susceptible to temptation.
Perhaps part of the reason Jesus died was to save him from a live of perpetual torment at being constantly tempted and having to constantly resist that temptation.
Just a thought!